This kind of laminated mold-making technique is a method of manufacturing a mold such as a core from computer data, for example CAD data, wherein a mold of complicated shape can be produced in a simple process.
Jpn. Pat. Appln. KOKAI Publication No. 2004-82206 discloses a method for manufacturing a mold by utilizing a laminated mold-making technique, wherein a water-soluble powder (for example, a salt powder) expanded in a plane is printed (sprayed through a nozzle) with a liquid (for example, an aqueous solution containing an adhesive substance such as gum arabic or starch) on the basis of CAD data by a three-dimensional printer having a nozzle, to make the bonding strength among particles of the salt powder in the sprayed region higher than that among particles of the salt powder in the unsprayed region, and then further expanding the salt powder thereon and similarly spraying the aqueous solution containing an adhesive substance thereon through the nozzle, is conducted repeatedly a desired number of times. This process is advantageous in that because the resulting mold is made of a water-soluble salt powder, the mold can be easily dissolved (removed) with water after casting.
However, the spray liquid contains an adhesive substance (for example, gum arabic, starch, etc.) and is highly viscous, so a nozzle may be clogged with the spray liquid when sprayed several times from a three-dimensional printer having a nozzle in producing a mold. When the viscosity of the spray liquid is reduced by decreasing the amount of the adhesive substance therein in order to prevent the clogging of the nozzle, the bonding strength among particles of the salt powder in the sprayed region may be reduced to cause collapse of the mold upon removal.